LU-1786 build: Fix build for crc32 pclmulqdq

LU-1786 build: Fix build for crc32 pclmulqdq

Old versions of gcc don`t know pextrd instruction. User mode
libcfs build had wrong dependency with ARCH variable defined.
PEXTRD marco was added for old gcc, wrong dependency was fixed.

Signed-off-by: Alexander Boyko <alexander_boyko@xyratex.com>
Change-Id: I8821a1c25367f0f284a80192ed65d89808d1b2da
Reviewed-on: http://review.whamcloud.com/3801
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Minh Diep <minh.diep@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>